Place freeze-dried strawberries in a food processor and blend until they become a fine powder. Measure 1 Tablespoon of the freeze-dried strawberry powder and combine with the sugar in a small bowl. Set aside.
Preheat oven to 225°F. Line a baking sheet with parchment paper. Set aside.
Wash and dry the bowl of a stand mixer (or a large, glass or metal mixing bowl) to ensure that it’s completely free of grease. Add the room temperature egg whites, salt, and cream of tartar to the bowl.
Using a stand mixer with the whisk attachment or a handheld electric mixer, stir the egg mixture on low speed until it becomes frothy. Then beat the mixture on high speed until it is no longer translucent and has doubled in volume.
Continue to beat the egg mixture on high speed while gradually adding the sugar mixture 1 Tablespoon at a time. Wait 10 seconds between adding each spoonful of sugar. (Adding the sugar too quickly could deflate the meringue.) Continue to beat the mixture until it becomes thick and stiff peaks form (see recipe note). Add vanilla extract and beat just until combined.
Transfer the meringue to a piping bag fitted with a star tip (I used a Wilton 1M piping tip). Holding the bag upright, pipe a tight swirl, beginning in the center and circling outward to create a rose shape. When you finish piping each rose, pull the bag away to the side rather than straight up to avoid creating any small peaks that could burn in the oven.
Bake for 45 minutes. Do not open the oven door during baking. When the meringues are finished baking, turn off the oven but still do not open the oven door. Allow the meringues to sit in the oven for 1 hour before removing the baking sheets from the oven and allowing them to cool completely on a wire rack.
Once completely cooled, decorate the meringue roses with pearl sprinkles (if using).